Mood = :proud:
I had to use some setTimeout calls in order to ensure that the objects I was referring to were present. There is a particularly long timeout of 5 seconds that allows the dialog to hopefully complete rendering before it attempts to launch the popup with the tree view that actually selects the destination. All efforts to encapsulate this in the dialog's onload function met with failure. Perhaps one day I'll work that one out. Closing the dialog will refresh the view. This should work for any list or library in your SharePoint web application. Unfortunately there is no URL token corresponsing to the guid of the web application, so this will need to be provided as a hard-code value as I have done. I hope this is helpful to someone, as it took quite a lot of trial and error.